Three disease genes for Leber Congenital Amaurosis (LCA), early onset Retinitis Pigmentosia (RP) and Cone-Rod Dystrophy (CRD) were discovered in 1996 and 1997. Each of the genes has been implicated in LCA, RP or CRD. These are recessively inherited disorders that lead to visual impairment and blindness of pediatric patients. The three genes are: 1) CRX, involved in opsin expression and photoreceptor differentiation; expressed in the photoreceptors; 2) RetGC, Retinal Guanylyl Cyclase; also expressed in the photoreceptors; and 3) RPE65, expressed in the retinal pigment epithelium; possibly the isomerase in the visual cycle. It is likely that these genes govern human retinal functions that can be evaluated by appropriate tests. Specific Aims: 1) Test patients with LCA, early RP, and CRD and family members for mutations of CRX, RetGC and RPE65 genes. 2) Use electroretinography (ERG), Dark Adaptation studies and Reflection Retinal Densitometry to test the hypothesis of altered retinal function. 3) Examine the genotypes and retinal phenotypes (that is, the parameters of retinal function) for significant relations.